Effects of dietary particulate limestone, vitamin K₃ and fluoride and photostimulation on skeletal morphology and osteoporosis in laying hens

Abstract

1. Female chicks of a White Leghorn strain were fed three different diets from one day old: control, additional vitamin K₃ (10 mg/kg), and a diet containing a combination of additional vitamin K₃, sodium fluoride (10 mg/kg) and limestone in particulate rather than powdered form. At 16 weeks photoperiod was increased for half the birds from 8:16 L:D to 16:8 L:D immediately or by one hour per week to the same ultimate photoperiod for the other half.

2. Age at first egg was lower by 4·0 d for birds on the fast lighting regime but there were no overall effects of lighting on bone quality at either 25 or 70 weeks.

3. Additional vitamin K₃ resulted in higher proximal tarsometatarsus cancellous bone volumes at 15 weeks and throughout the laying period compared with controls. Plasma osteocalcin concentrations were unaffected by vitamin K₃ supplementation during growth.

4. The combination diet resulted in beneficial responses of 12 to 20% in most bone characteristics in hens at 70 weeks. The magnitude of these effects was similar to a previous study involving a particulate calcium source alone (Fleming et al., Poultry Science, 39: 434–440, 1998 b). We conclude that the beneficial effects of the combined treatment over the lifetime of the hens were attributable mainly to the presence in the diet of a calcium source in particulate form.